Process of making screen-plates.



E. J. WELCH & A. GROCKER.

PROCESS OF MAKING SCREEN PLATES.

APPLIOATION FILED APR.30,1906.

91 9,505, Patented Apr, 27, 190 9.

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UNITED s'ra'rns PATENT OFFICE.

EDWARD J. WELGH AND ADAMS UROOKER, OF FITGHBURG, MASSACHUSETTS,ASSlGNORS TO UNION SCREEN PLATE COMPANY, OF FllGI-IB URG,MASSAOl'llTSEliIS, A CORPORA'JION ()l MASSACHUSETTS.

PROCESS OF MAKING SCREEN-PLATES.

Specification of Letters Patent.

Patented April 27, 1909.

To all whom it may concern:

Be it known that we, EDWARD J. 'nLon and ADAMS CROCKER, citizens of theUnited States, and residents of Fitchburg, county of Worcester, State ofMassachusetts, have invented an Improvement in Processes of MakingScreen-Plates, of which the following de scription is a specification.

This invention has for its object to provide a novel process for makingscreen plates for paper-making machines.

Heretofore it has been a more or less common practice to make screenplates from composition ingots which are first cast in metal molds andthen are reduced to the proper size and thickness for the screen plateby repeated rollings, the plate being subjected to an annealing processbetween each rolling. The repeated rollings of the ingot render ithomogeneous and close up any blow holes that may exist, and theintermediate annealing process keeps the plate in proper condition forrolling. been reduced to its proper size and thickness by these repeatedrollings, it is given the desired temper, and then the slots eut in itas usual.

Obviously the making of a screen-plate according to this processconsumes considerable time owing to the repeated rollings and annealingsto which the plate is subjected. Furthermore this process cannot besuccessfully carried out unless the alloy or composition from which theingots are poured has the proper ingredients.

A screen-plate made from copper and a proper amount of tin has suchproperties that it can be reduced to the proper size by the repeatedrollings, as stated above, but such a screen-plate is apt to be so hardthat the slots therein can only be cut with dithculty.

If sufficient lead, or lead and tin combined, or similar in redients areadded to the alloy the plate will have such a structure that the slotscan be more easily and perfectly cut therein; but if a plate made from acopper alloy containing lead, or lead and tin, etc., in sufficientquantities is subjected to repeated rollings the plate will assume afractured or cracked character and will lack the homogeneity necessaryin screen-plates. The presence of lead in the alloy also has theadvantage that it tends to increase the acid resisting properties of thescreen plate. There hen the plate has are, therefore, many advantages inusing for a screen plate an alloy including load, or lead and tincombined, or a similar material, but as it has been found inexpedient tosubject a screen-plate made of such alloy to repeated rollings, it hasbeen customary to make plates of this alloy by casting the ingot in asand mold (a sand mold being used in order to obtain as perfect acasting as possible and one as free from blow holes as possible) andthen machining the casting to reduce it to the required dimensions, thisbeing the only way in which a composition having the desired amount oflead, or lead and tin com bined, has been heretofore treated. While ascreen-plate made in this way has the pro per acid resisting properties,and is of such a character that the slots can be readily and cleanly cuttherein, yet such a sci'een-1')late cannot be properly tempered by anyknown tempering process, and when completed it is dead metal, and hasnot sullicient life to enable it to withstand the abuse to whichscreen-plates are put.

\Ve have discovered that a screen-plate having the proper temper, theproper structural characteristics to enable the slots to be cut cleanly,and the proper acid resisting properties, may be made by first castingin a sand mold an ingot of a suitable composition, which ingot isapproximately the size and thickness of the completed screenplate, thenmachining the ingot so as to smooth up the surfaces thereof and reduceit to very nearly the thickness of the completed screenplate, and thencold-rolling the trued-up plate, this cold-rolling process resultingboth in reducing the plate to exactly the required thickness and alsooperating to give it the proper temper which is so essential to anarticle of this character.

Te have found from experiments that a suitable alloy from which to makescreenplates according to this process is one comprising substantially82% copper, 12% tin, 3% lead and 3% zinc. The presence of the zinc inthe alloy helps to make the casting sound and free from blow holes, andthe presence of the tin tends to make the casting tough.

Aplate made of this alloy could not be subjected to repeated rollingswithout giving it the cracked or fractured character above describedowing to the presence of lead in combination with the tin, but we havedemonstrated that cold-rolling the trued-up plate once does not affectit deleteriously. In fact cold-rolling it once has decidedly beneficialresults as it gives to it the proper temper. A plate made from the abovedescribed alloy has sufiicient lead in it so that the slots t h epgipcan be readily andsmonthlgnciih, but

unless the late is tem ,cred in some wa it u I )1 P y would be deadstand the severe wear to which screen-plates are put. Cold-rolling thisplate once or so gives to it the necessary life and temper, but does notdestroy the structure as repeated cold-rollings would. Casting the ingotin a sand lnold renders it suli stantially homogeneous and free fromblow holes so that repeated rollings are unnecessary and the casting ofthe ingot to substantially the desired thickness and shape reduces theamount of work necessary to reduce the ingot to the size and shape ofthe finished screen-plate. All that is necessary is to true-up the ingotand then to subject it to this one cold rolling 5 and would lack theresili- 1 ency and life necessary to cause it to withfinished plate whenmade in accordance With our improved process.

In the drawings wherein We haveillustrated more or less diagrammaticallythe manner of carrying out the above described process Figure 1 showsthe cast ingot in perspective; Fig. 2 shows the process of truing up theingot Fig. 3 shows the cold-rolling process.

The ingot is designated by 3 and it may be cast in sand in any usualway. After it is cast, as stated above, it is trued up by a suitablemachine; and to illustrate this step in the process Fig. 2 shows a tool4 acting on the face of the ingot for truing up the surface thereof. Thefinal step of the process is the cold-rolling which may be convenientlydone by placing the trued-up ingot between rolls 6 and 7 in any suitableway.

Having fully described our invention what we claim new and desire tosecure by Letters Patent is:

The steps in the process of manufacturing screen plates which consistsin first casting an ingot of a copper alloy having lead therein, secondtruing up the casting and reducing it to substantially the size desiredfor the screen plate, and thirdtempering the truedup casting bycold-rolling.

In testimony whereof, we have signed our names to this specification, inthe presence of two subscribing witnesses.

EDI WARD J. IWELGH. ADAMS CROCKER.

IVitnesses EDWARD B. FARRAR, IVALTEP. G. COREY.

